Effects of vortex and antivortex excitations in underdoped Bi₂Sr₂Ca₂Cu₃O10+δ bulk single crystals

The observance of vortex and anti-vortex effects in bulk crystals can prove the existence of phase-disordered superconductivity in the bulk. To gain insights into the mechanisms that govern superconducting transition in copper oxide high-transition temperature (Tc) superconductors, this study investigated the transport properties of underdoped Bi₂Sr₂Ca₂Cu₃O10+δ (Bi-2223) bulk single crystals.The I-V characteristics results and the typical tailing behavior owing to the temperature dependence of in-plane resistivity (ρab) were consistent with the Kosterlitz-Thouless (KT) transition characteristics. Thus, with increasing temperature, copper oxide high-Tc superconductors transitioned to their normal state owing to destruction of their phase correlations, although a finite Cooper pair density was prevalent at Tc. Further, magnetization measurements were performed to determine the temperature dependence of the irreversible magnetic field Bᵢᵣᵣ. Consequently, the mechanism governing the KT transition-like superconducting transition in this bulk system was elucidated. These results support the extreme strong-coupling models for high-Tc superconductivity in cuprates.